This paper presents the concept of a convoy of autonomous electric vehicles which will be able to continue its mission in the presence of some actuator or sensor faults. The autonomous vehicle is called RobuCar which is constituted by four independently driven wheels and two independently adjustable steering angles. Firstly, we develop longitudinal and lateral controllers for the vehicles operating normally. The objective is to follow a reference trajectory and to maintain safe spacing between vehicles. Secondly, we develop some strategies based on fault detection and isolation results in order to reconfigure the convoy of vehicles in presence of faults. Three categories have been considered: sensor or actuator fault which has not altered the trajectory; fault that affects the velocity or disturbs the trajectory; faults that make impossible for the vehicle to continue its mission. Simulation results are given at the end to show the efficiency of the approach.
Predicting how the electric vehicle (EV) market will develop is important not only to countries, such as Japan, that have been leading the car market but also for developing countries. Thus, in order to predict the diffusion of electric vehicles, this study quantitatively analyzes the diffusion speed and price transition of existing cars and clarifies the optimum prediction method for cars' diffusion rates. A prior study examined the diffusion speed and price transition of new products after the commencement of sales using consumer electronics products and cars. It demonstrated the key roles played by engineering development and a key device's production and sales for each product. This study applies that result to other new products and embodies the predictive method as a general formula. It also increases predictive accuracy by extending the subjects of investigation the home electric appliances. The results show that the development speed of the key devices and the diffusion speed of the products are strongly correlated; this fact is expressed as an empirical equation. Furthermore, the general formula for predicting the transition of diffusion rates and prices was produced through an analysis of the empirical equation. By predicting the diffusion speed of an electric vehicle through the empirical equation and its general formula, the study shows that an EV similar to a compact car will have a 20 % household penetration rate in about 15 years after sales commence and that EVs smaller than a mini car will achieve 20 % in 8.7 years.
The performance test of four different martial lead acid (Li-Acid), Nickel cadmium (Ni-Cd), lithium-ion (Li-Ion) and nickel metal hydride (NiMH) batteries for 4WD electric vehicle under several speeds variation constraints are presented in this paper. The battery materials model choice is a key item, and thanks to an increasing importance on vehicle range and performance, the Li-Acid, Ni-Cd,Li-Ion and NiMH batteries could become a viable candidate that's our proposal battery model in the present work , in this way the present paper show a novel strategy of 4WD electrical vehicle power electronics studies when the current battery take into account the impact of the direct torque based space vector modulation technique (DTC-SVM) in the several speed variations using the primitive battery SOC of 75 % state. The speed of four wheels is calculated independently during the turning with the electronic differential system computations which distributes torque and power to each in-wheel motor according to the requirements, adapts the speed of each motor to the driving conditions This paper focuses lead acid ,Lithium-ion and NiMH Batteries controlled by Buck Boost DC-DC converter power supply for EV. The performances of the proposed strategy controller give a satisfactory simulation results. The proposed control law increases the utility EV autonomous under several roads topologies.
This paper first proposes a multilayer framework of vehicle-to-grid (V2G) system based on the concept of gridable vehicles (GVs). GVs can draw and store energy from the power grid as loads, as well as feed energy back to the grid as resources. Then, unit commitment integrating with GVs is analyzed using the proposed framework. The objective is to minimize the total operating cost and emissions of the V2G system by intelligently scheduling the generating units and GVs based on the use of genetic algorithm. The results illustrate that the operating cost and emissions can be reduced and the system reserves can be enhanced by applying V2G.
In this study, we design autonomous navigation, guidance and control system for small four-wheel ground vehicle. Small and low-accuracy sensors (low-cost GPS, low-accuracy accelerometers) are only used for navigation and control of the UGV. Firstly, INS/GPS composite navigation system is designed to obtain high-accuracy position and velocity of the vehicle by using low-accuracy sensors. Secondly, velocity and heading controller for the vehicle are designed. Lastly, novel guidance method based on spline interpolation is proposed for precise guidance of the UGV. Whole systems designed in this research are validated by the simulation and experiments.
Predicting the tractive limitations of locomotion gears is of critical importance in a robotic vehicle system on natural terrain. In particular, it is imperative for an unmanned mobile robot to avoid getting stuck in loose soil to retain its mobility. From this perspective, this paper attempts to theoretically predict the limitations of a typical wheel in such loose soil based on traditional soil-wheel interaction models. In the case that the model brings a negative drawbar pull exerted by the wheel under any kinematic slip condition, we analytically investigated the limitations using a ratio of sinkage over the wheel radius. Predicted limitations are suggested for design optimization and control of the wheeled vehicle. Furthermore, this paper presents the relationship between the model analysis and a practical single wheel test, which provides significant guidelines for usage of the experimental results.
This paper presents the effectiveness of the flexible wheels for lunar exploration rovers. The flexible wheels give high performance while traversing loose soil. The flexible wheel is an effective scheme to traverse loose soil without poor performance. The flexible wheel has a surface which can be changed flexibly for rough terrain. When the surface of wheel performs matching the shape of ground it is crossing, the normal stress between the wheel and loose soil becomes small. It is prevented from sinking because this normal stress is small. However, the flexible wheel doesn't have high performance without grousers. The grouser is very important to get thrust for rovers. From running experiments using a single wheel tester, we found that the flexible wheel with grousers gave a high performance. The mounted positions of grousers on the surface of the wheel are defined by the same angle (ex) 36 deg). This means that there are two patterns to mount grousers. One is under the rib while the other is between the ribs. The spring force under the rib is different from between the ribs, it is greater. Moreover, each distortion is different. From these considerations, we need to find the optimal position for grousers. We carried out running experiments using wheels with both patterns. From our experiments, we understood the wheel with the position mounted between ribs gave a better performance than when it was set under the rib. When the area giving normal stress is wide, soil under the wheel becomes hard. Therefore, the wheel with grousers mounted between ribs gives a higher performance compared with the one mounted under the ribs.